ANIMATED DRAWINGS DESCRIBE THE RELATION BETWEEN RAINFALL & LIFE; THE SOURCES OF CITY WATER SUPPLY; WELLS, RIVERS, LAKES & WATERSHEDS; WATERBORNE DISEASES & METHODS OF WATER DISTRIBUTION.
Appraisal. Very good for (1) indicating the importance of water to living things, (2) showing New York City's water-supply system, and (3) demonstrating some of the procedures used in safeguarding a water supply from pollution and disease. Should be useful in developing an appreciation of a most important public service, and in stimulating detailed study of the local water-supply system.
Animation is cleverly used in clarifying many points in the film. The film will be of particular interest to classes in the areas contributing to or served by the New York City water-supply system.
Photography and sound are excellent.
Contents. How New York City gets its water and how that water is protected from pollution, shown in animation and straight photography.
As views of animals drinking are shown, the commentator says that water is essential to all living things. There follow views of rain, streams, forests, grasslands, and deserts as the commentator explains the importance of rainfall to vegetation.
The sources of water used by man are indicated. Water is dipped from a spring and drawn from a well. It is shown that large wells used by cities tap underground water supplies. Lakes and rivers are shown as sources from which some cities draw their water supply.
The remainder of the film explains the operation of a large city water-supply system. Watersheds, lakes, and aqueducts are shown, and their place in the water system explained. There are views of a grade tunnel that carries water through a mountain, and of the pressure tunnel that carries the water under the Hudson River. The various watersheds, lakes, and aqueducts are identified by name.
A sewage treatment plant is shown as the commentator says that such plants reduce the pollution caused by sewage and industrial waste. In a laboratory, microscopic examination is made of a water sample. A measured amount of water is placed in a culture medium, incubated, and the resulting colonies of bacteria observed. Tests for alkalinity, solids, and excessive nitrogen content and turbidity are briefly suggested. It is shown that, when water stands for some time in a lake or reservoir, the suspended matter settles out. The use of alum in precipitating suspended matter is demonstrated. Lime is added to reduce the acidity caused by the alum. The use of sand filters, the addition of carbon, aeration, and chlorination are also shown as means of safeguarding the water supply.
Beginning with the tunnels that lead the water into the city, the system that distributes the water to the consumer is shown. The water continues on its way through risers and mains. The commentator says that, while gravity flow brings the water into the city, at some points pressure pumps are required. There is a view of the pressure pumps. A series of views indicate the many uses of water in a city.
ANIMATION WATER DISEASES RAIN CITIES RIVERS LAKES WATERSHEDS DRAWINGS CITY SERVICES HEALTH AND SAFETY RESERVOIRS FOUNTAINS Danger Lurks